The present invention relates to an optical disk apparatus capable of recording and reproducing information and to a method of installing spindle motor in the optical disk apparatus.
In recent years, optical disk apparatuses which read and reproduce information on an optical disk used as a recording medium by using an optical pickup have become smaller in size and higher in performance. Portable MD players using minidiscs have become generally widespread as portable optical disk apparatuses.
A portable MD player disclosed in the Japanese Unexamined Patent Publication No. Hei 11-96747 will be described below as an example of a conventional optical disk apparatus.
FIGS. 11A and 11B are sectional views showing the conventional portable MD player disclosed in the Japanese Unexamined Patent Publication No. Hei 11-96747. Referring to FIGS. 11A and 11B, the portable MD player has an outer case 101 comprising an openable upper lid 101a and a lower case 101b which rotatably holds the upper lid 101a. FIG. 11A shows a condition wherein the upper lid 101a is open, and FIG. 11B shows a condition wherein the upper lid 101a is closed and makes contact with the lower case 101b. 
As shown in FIG. 11A, a minidisc case 102 (hereafter referred to as an MD case) accommodating an optical disk 100 is loaded while the upper lid 101a is opened. A variety of information such as music information has been recorded on the optical disk 100. A spindle motor 103 is disposed at the nearly central area of the lower case 101b. A turntable 104, on which the optical disk 100 inside the MD case 102 is to be put and rotated, is provided at the upper portion of the spindle motor 103.
In addition, an optical pickup 105 for reading information from the optical disk 100 accommodated in the MD case 102 and a feeding mechanism 106 for moving the optical pickup 105 in the diametric direction of the optical disk 100 are provided inside the lower case 101b. Numeral 107 designates a feeding shaft used as a component of the feeding mechanism 106. This feeding shaft 107 is rotatably supported by the chassis (not shown) of the feeding mechanism 106. The optical pickup 105 screw-engaged with the feeding shaft 107 is moved in the diametric direction of the optical disk 100 by the rotation the feeding shaft 107.
Furthermore, electric components and electric circuits required for playing the optical disk 100 inside the MD case 102 are disposed at the lower portion of the feeding mechanism 106 inside the lower case 101b. 
In the conventional portable MD player configured as described below, the relative distance between the optical pickup 105 and the optical disk 100 is required to be set within an allowable range in order to securely read the information of the optical disk 100. In other words, the recording face of the optical disk 100 is required to be set to have a tilt within a predetermined range (not more than a standard value) with respect to the movement axis of the optical pickup 105. If the above-mentioned relative distance is not constant, and the focal length of the lens of the optical pickup 105 is not aligned with the recording face, the information of the optical disk 100 cannot be read properly.
Moreover, if the recording face of the optical disk 100 is not parallel but significantly tilted with respect to the movement axis of the optical pickup 105, the laser light emitted from the lens of the optical pickup 105 is reflected by the optical disk 100 and not fed back to the lens. Therefore, the information of the optical disk 100 cannot be read accurately.
The conventional optical disk apparatus having the above-mentioned configuration causes the following problems. If the optical disk 100 mounted on the turntable 104 of the spindle motor 103 is not parallel but tilted with respect to the movement axis of the optical pickup 105, and if the tilt is not within the allowable range, the information recorded on the optical disk 100 cannot be read accurately. For this reason, it is necessary to accurately assemble the turntable 104 on which the optical disk 100 is mounted and the feeding mechanism 106 of the optical pickup 105 at the time of assembling the conventional optical disk apparatus.
FIG. 12 is a partially sectional view showing the relationship between the optical disk 100 on the turntable 104 and the optical pickup 105 of the conventional optical disk apparatus. In the example shown in FIG. 12, a bracket 103a to which the spindle motor 103 is secured is tilted with respect to a chassis 108. As a result, the turntable 104 is assembled greatly tilted with respect to the movement axis of the optical pickup 105.
It is provided that the disk mounting face 104a of the spindle motor 103 installed on the chassis 108 is tilted at angle a for example with respect to the movement axis of the optical pickup 105 in the movement direction thereof as shown in FIG. 12. In this case, the relative distance A between the lens 105a of the optical pickup 105 and the recording face of the rotating optical disk 100 changes greatly, thereby greatly exceeding a predetermined allowable range (standard value) and causing a problem. The angle xcex1 is an angle between the rotation center axis of the spindle motor 103 and an axis perpendicular to the movement axis of the optical pickup 105. As a result, the focal length of the laser light from the optical pickup 105 is not aligned with the recording face of the optical disk. It thus becomes impossible to read the information of the optical disk 100.
In addition, variations in the tilt of the rotation axis of the spindle motor 103 and variations in the height of the rotation axis thereof with respect to the recording face of the optical disk 100 are relatively large when the spindle motor 103 is smaller. Therefore, in order to decrease the variations in the tilt and height of the spindle motor 103, it is necessary to raise the machining accuracy of the components of the spindle motor 103 or it is necessary to measure the dimensions of completed components and to select and use the components having dimensions within predetermined ranges. For example, when a specific figure is given for the tilt of the spindle motor 103, the tilt has a very narrow allowable range of about xc2x10.1 degree (in all directions) in the case of the MD player. Therefore, the spindle motor 103 of the conventional portable MD player has low productivity, resulting in high cost.
To solve the above-mentioned problems, the present invention is intended to provide an optical disk apparatus wherein the tilt of a loaded optical disk is set within a predetermined range. This is attained by adjusting the relative distance between the lens of an optical pickup and the recording face of the optical disk even if the disk mounting face of a turntable is tilted with respect to the movement axis of the optical pickup and the height of the disk mounting face varies considerably because the installation position of a spindle motor is tilted with respect to a chassis. The present invention is further intended to provide a method of installing the spindle motor for use in the optical disk apparatus.
An optical disk apparatus in accordance with the present invention comprises:
reading means for reading information from a disk on which information is recorded,
movement means for moving the reading means in parallel with the recording face of the disk,
a spindle motor having a turntable on which the disk is mounted and rotated and having a bracket secured thereto,
a chassis having plural spindle motor support portions to support the bracket, on which the movement means is fixed and the reading means is movably held, and
height correction means which calculates a height, whereat the spindle motor is supported by the spindle motor support portions on the basis of the tilt and height data of the disk mounting face of the turntable with respect to a reference plane and on the basis of the tilt and height data of a plane formed by the plural spindle motor support portions on the chassis with respect to the reference plane and for correcting the heights of the spindle motor support portions on the basis of the result of the calculation.
In the optical disk apparatus in accordance with the present invention configured as described above, the positional relationship in tilt and height between the reading means and the disk mounted on the turntable can be corrected accurately even if the disk mounting face of the turntable of the spindle motor has variations in tilt and height.
Furthermore, in the optical disk apparatus in accordance with the present invention, the height correction means carries out correction by installing spacers having desired thicknesses on the spindle motor support portions when the heights of the spindle motor support portions obtained as the result of the calculation have minus values. On the other hand, when the heights of the spindle motor support portions obtained as the result of the calculation have plus values, the height correction means carries out correction by grinding the spindle motor support portions so that they have desired heights.
Furthermore, in the optical disk apparatus in accordance with the present invention, data regarding the tilt and height of the disk mounting face with respect to the bracket of the spindle motor is written on a part of the spindle motor. Therefore, in the optical disk apparatus in accordance with the present invention, it is possible to quickly make a decision as to whether spacers having proper thicknesses are selected on the basis of the result of the calculation or the support portions are ground so that they have proper heights on the basis of the result of the calculation by simply reading data from the spindle motor. Therefore, productivity can be improved greatly.
A method of installing the spindle motor of the optical disk apparatus in accordance with the present invention, in an assembling process for the optical disk apparatus having
reading means for reading information from a disk on which information is recorded,
movement means for moving the reading means in parallel with the recording face of the disk,
a spindle motor having a turntable on which the disk is mounted and rotated and having a bracket secured thereto, and
a chassis having plural spindle motor support portions to support the bracket, on which the movement means is fixed and the reading means is movably held, comprises:
a step of measuring and calculating the tilt and height of the disk mounting face of the turntable with respect to a reference plane, and
a step of carrying out calculation for height correction in accordance with the results of measurement and calculation on the basis of data regarding the turntable and correcting the heights of the spindle motor support portions on the basis of the result of the calculation.
In the optical disk apparatus assembled as described above, the positional relationship in tilt and height between the reading means and the disk mounted on the turntable can be corrected accurately even if the disk mounting face of the turntable of the spindle motor has variations in tilt and height. Therefore, it is possible to obtain a highly reliable optical disk apparatus.
A method of installing the spindle motor of the optical disk apparatus in accordance with the present invention from another point of view, in an assembling process for the optical disk apparatus having
reading means for reading information from a disk on which information is recorded,
movement means for moving the reading means in parallel with the recording face of the disk,
a spindle motor having a turntable on which the disk is mounted and rotated and having a bracket secured thereto, and
a chassis having plural spindle motor support portions to support the bracket, on which the movement means is fixed and the reading means is movably held, comprises:
a step of measuring and calculating the tilt and height of the disk mounting face of the turntable with respect to a reference plane,
a step of measuring and calculating the tilt and height of a plane formed by the plural spindle motor support portions on the chassis with respect to the reference plane, and
a step of carrying out calculation for height correction in accordance with the results of measurement and calculation on the basis of data regarding the turntable and the chassis and correcting the heights of the spindle motor support portions in accordance with the result of the calculation.
In the optical disk apparatus assembled as described above, the positional relationship in tilt and height between the reading means and the disk mounted on the turntable can be corrected accurately even if the plane formed by the spindle motor support portions has variations in tilt and height with respect to the reference plane. This is attained since the height data of the spindle motor support portions on the chassis is used in addition to the tilt of the disk mounting face of the turntable. Therefore, it is possible to obtain a highly reliable optical disk apparatus.
A method of installing the spindle motor of the optical disk apparatus in accordance with the present invention from another point of view, in an assembling process for the optical disk apparatus having
reading means for reading information from a disk on which information is recorded,
movement means for moving the reading means in parallel with the recording face of the disk,
a spindle motor having a turntable on which the disk is mounted and rotated and having a bracket secured thereto, and
plural spindle motor support portions to support the bracket, on which the movement means is fixed and the reading means is movably held, and plural movement means support portions for supporting the movement means, comprises:
a step of measuring and calculating the tilt and height of the disk mounting face of the turntable with respect to a reference plane,
a step of measuring and calculating the tilt and height of a plane formed by the plural spindle motor support portions on the chassis with respect to a reference plane,
a step of measuring and calculating the tilt and height of a plane formed by the plural movement means support portions on the chassis with respect to the reference plane, and
a step of carrying out calculation for height correction in accordance with the results of measurement and calculation on the basis of data regarding the turntable and the chassis and correcting the heights of the spindle motor support portions in accordance with the result of the calculation.
In the optical disk apparatus assembled as described above, the positional relationship in tilt and height between the reading means and the disk mounted on the turntable can be corrected accurately even if the plane formed by the movement means support portions has variations in tilt and height. This is attained since the height data of the movement means support portions on the chassis is used in addition to the tilt data of the disk mounting face of the turntable and the height data of the spindle motor support portions on the chassis.
While the novel features of the invention are set forth particularly in the appended claims, the invention, both as to organization and content, will be better understood and appreciated, along with other objects and features thereof, from the following detailed description taken in conjunction with the drawings.